It is known to secure two webbing straps together by the use of a buckle assembly. The buckle assembly is secured to one webbing strap and a lug is attached to the other webbing strap. The lug is securely but releasably retained in a socket of the buckle assembly. The lug is released from the socket arrangement in response to a user manually operating a button, switch, lever or other user operated input.
Such buckle assemblies are widely used in harness arrangements in aircraft. Attachment of a pilot to the ejection seat of the aircraft is normally by means of a conventional multi-point harness having a central connection block to which numerous webbing straps are connected. The multi-point connection block, incorporating a buckle assembly, is usually provided on a strap (the “negative-G strap”) connected to or adjacent the seat squab of the ejection seat. The strap passes between the legs of the pilot for connection of shoulder and lap webbing straps to the connection block.
It is necessary for a buckle assembly to afford quick manual attachment and detachment of the socket arrangement and lug(s) in normal use. At the same time, operation of the buckle assembly must be reliable and ensure secure retention of the lug(s) in the socket arrangement when desired. Any inadvertent, undesired, release of the lug from the socket arrangement must be prevented.
When a pilot ejects from an aircraft, the pilot will remain secured to the ejection seat for a predetermined period of time, at least until the parachute has fully deployed. In some situations, the pilot may remain attached to the seat substantially until the pilot lands. Particularly when landing on water, it is preferable for the pilot to remain close to the ejection seat, since it houses numerous survival provisions, such as a life-raft, flares, food etc.
Nevertheless, when landing in water, it is essential that the pilot is separated from the ejection seat as soon as possible, so that the pilot can swim free from the ejection seat.
It is known to provide a water-activated buckle assembly which, upon the detection of water, automatically releases the buckle assembly and therefore the pilot from the seat. Known systems comprise a water sensor located remote from the buckle assembly and operably connected by an actuator to the buckle assembly. In a known arrangement, a buckle assembly comprises a sacrificial pyrotechnic squib which, in response to a trigger condition from a water sensor, initiates to release the plurality of lugs from the buckle assembly. Such an arrangement is only a single use item since, once activated, the assembly will no longer be operable to receive and retain a lug in the assembly.
It has been known for such water-activated buckle assemblies to be inadvertently triggered. For example, a pilot may accidentally spill liquid over the water sensor. Alternatively, one of the components of the assembly (e.g. sensor, squib) may fail, causing triggering of the assembly. This causes the buckle assembly to automatically release the harness arrangement, with no provision to re-secure the lugs to the connection block. When a conventional water-sensing buckle assembly has been triggered, there is no way to reattach the lugs to the buckle assembly. The spent trigger system (i.e. the squib) must first be replaced before normal operation of the buckle assembly can be restored. This is clearly undesirable, particularly if the inadvertent release occurs during flight. There is a need for a reliable buckle assembly which seeks to address at least one of these problems.